Thermal spraying robots are conventionally known in which movement path patterns for a plasma jet torch consisting of a series of identical subpatterns are generated based on taught data and the torch is moved in a plane in accordance with the generated patterns.
In thermal spraying robots, before spraying is carried out, an operator teaches the robot start and end points of a first subpattern, individual cornering points between the start and end points, and a subpattern shift amount (consisting, for example, of the component of a shifting direction and the component of a direction perpendicular to the shifting direction). When taught individual points, the robot stores, in a pattern file, joint angles (taught data) of individual robot axes for positioning the torch at the respective taught points. Also, when the subpattern shift amount is taught, it is stored in the file.
In a spraying operation, the robot first carries out spraying on tile first portion of a spraying plane in accordance with the first subpattern generated based on the taught data read from the pattern file. Subsequently, in accordance with the next subpattern generated by adding the shift amount to the individual points of the first subpattern, the robot effects spraying on a portion of the plane adjacent to the already sprayed portion. Thereafter, a similar operation is repeated in accordance with the subpatterns successively generated, to complete a spraying operation over the entire spraying plane.
In the conventional robot mentioned above, when the distance (pitch) between adjacent ones of pattern segments constituting a subpattern and extending perpendicularly to the direction of pattern shifting is to be varied, the start point, individual cornering points, and end point of the subpattern and the subpattern shift amount must be taught again. This requires much effort and additional teaching. Particularly, when a high pattern generation accuracy is required, the teaching process must be executed carefully and thus the teaching process becomes quite time consuming.